1. Technical Field
The present invention relates to an automatic screw tightening apparatus which automatically tightens a screw against a predetermined screwed portion of a subject by a screw tightening mechanism.
2. Related Art
In an automatic screw tightening apparatus according to the related art for automatically tightening a screw against a predetermined screwed portion of a subject by a screw tightening mechanism as disclosed in Japanese Patent Application Laid-Open No. Hei8-229752, predetermined screws are automatically fed from a screw feeding mechanism to a screw tightening head of a fore end of the screw tightening mechanism one by one. Then, the subject is fixed to a movable table and the screwed position of the subject moves to a predetermined position while the screw tightening head of the screw tightening mechanism moves. Next, the screw is tightened to assemble the subject.
In this case, screws are fed to the screw tightening mechanism through a feeder hose. However, there are disadvantages as follows. For example, tips of screws often get stuck in the hose. Further, since the screw feeding mechanism should move with the feeder hose attached to the screw tightening head, the screw feeding mechanism is large. Furthermore, since the moving range of the screw tightening mechanism should be wide, the screw tightening apparatus is disadvantageous in space. Moreover, unexpected accidents may happen due to contact of workers or subjects with the hose or others.
Meanwhile, screw tightening mechanisms in which a driver bit unit sucks air from a gap between a driver bit (BIT) and a screw holder so as to engage a screw with the driver bit and hold the screw are disclosed in Japanese Patent Application Laid-Open No. Hei8-229752, Japanese Patent Application No. 2010-29559 filed previously by the applicant of the present application, etc.